Recorded Liabilities and Major Assumptions Underlying Future Policy Benefits (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits		$ 37,063	$ 36,475
Long Term Care Insurance Contracts
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[1]	$ 21,590	$ 20,563
Long Term Care Insurance Contracts | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[1]	3.75%	3.75%
Long Term Care Insurance Contracts | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[1]	7.50%	7.50%
Structured Settlements with Life Contingencies
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[2]	$ 8,858	$ 8,991
Structured Settlements with Life Contingencies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	1.00%	1.00%
Structured Settlements with Life Contingencies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	8.00%	8.00%
Annuity Contracts with Life Contingencies
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[2]	$ 3,822	$ 4,010
Annuity Contracts with Life Contingencies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	1.00%	1.00%
Annuity Contracts with Life Contingencies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	8.00%	8.00%
Traditional Life Insurance Contracts
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[3]	$ 2,506	$ 2,638
Traditional Life Insurance Contracts | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[3]	3.00%	3.00%
Traditional Life Insurance Contracts | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[3]	7.50%	7.50%
Supplementary Contracts with Life Contingencies
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[2]	$ 284	$ 269
Supplementary Contracts with Life Contingencies | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	1.00%	1.00%
Supplementary Contracts with Life Contingencies | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[2]	8.00%	8.00%
Accident and Health Insurance Contracts
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits	[4]	$ 3	$ 4
Accident and Health Insurance Contracts | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[4]	3.50%	3.50%
Accident and Health Insurance Contracts | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Future policy benefits, Interest rate assumption	[4]	6.00%	6.00%

[1] The 1983 Individual Annuitant Mortality Table or 2000 U.S. Annuity Table, or the 1983 Group Annuitant Mortality Table or the 1994 Group Annuitant Mortality Table and company experience.

[2] Assumptions for limited-payment contracts come from either the U.S. Population Table, the 1983 Group Annuitant Mortality Table, the 1983 Individual Annuitant Mortality Table, the Annuity 2000 Mortality Table or the 2012 Individual Annuity Reserving Table.

[3] Principally modifications based on company experience of the Society of Actuaries 1965-70 or 1975-80 Select and the Ultimate Tables, the 1941, 1958, 1980 and 2001 Commissioner's Standard Ordinary Tables, the 1980 Commissioner's Extended Term table and (IA) Standard Table 1996 (modified).

[4] The 1958 and 1980 Commissioner's Standard Ordinary Tables, or the 2000 U.S. Annuity Table, or the 1983 Group Annuitant Mortality.